Investigators are trying to determine what caused the fire, including digging up the gas line to the house.

“To say what is the cause at this time is still way too early,” said Deputy Fire Chief Michael O’Brien. “It’s still quite an active investigation.

Although the cause is not known, there is no danger to the surrounding homes, fire officials said.

“This seems to be just isolated to this structure,” O’Brien said.

The name of the victim will not been released until the family is notified.

The fire broke out around 2 p.m. and quickly went to two alarms as firefighters worked to contain it.

“You can see by one of the adjacent buildings, the intensity of the fire, we did get a line on that building and limited the fire to the original fire building,” O’Brien said.

Neighbor Andrew Morrissey was one of the first people on the scene, but there was little he could do.

“We could see the smoke and then we heard some noises, so we just ran up,” Morrissey said. “By the time we got there, the whole house was in flames. It was torched.”

Kyra Kirkland also lives nearby and felt what she described as an explosion.

“It was just like a big boom,” Kirkland said. “It was like the house shook a little and I looked out the window and the smoke was going everywhere. It was engulfed. The roof gave and then the fire was spouting through the roof.”

FROM THE WZID TRAFFIC NETWORK, I'M SUZANNE ROANTREE. THANKS. WE COULD LEARN TODAY WHAT CAUSED A DEADLY FIRE DOWN IN NASHUA. THE FLAMES BROKE OUT AT THE HOUSE ON CARLISLE ROAD WEDNESDAY AFTERNOON. INVESTIGATORS ARE NOT YET SAYING HOW THE VICTIM DIED. WITNESSES SAY THEY HEARD EXPLOSIONS AND THEN SAW FLAMES SHOOTING OUT OF THE HOUSE. RAY BREWER JOINS US LIVE IN NASHUA WITH THE TOP STORY. ERIN, SOME FIREFIGHTERS AND FIRE TRUCK HAVE JUST SHOWN UP HERE ON THE SCENE AT CARLISLE ROAD IN NASHUA. INVESTIGATORS YESTERDAY DID CHECK THE GAS LINES GOING INTO THE HOME. AT THIS POINT, IT IS NOT CLEAR HOW THE FIRE STARTED. INVESTIGATORS WORKED THE SCENE, TRYING TO FIGURE OUT WHAT CAUSED THE FATAL HOUSE FIRE IN NASHUA. THAT INCLUDES DIGGING UP THE GAS LINE LEADING INTO THE HOUSE. HOWEVER, INVESTIGATORS SAY THEY ARE NOT READY TO DRAW ANY CONCLUSIONS. TO SAY WHAT IS THE CAUSE AT THIS PARTICULAR TIME IS WAY TOO EARLY. STILL AN ACTIVE FIRE INVESTIGATION. OFFICIALS ARE NOT RELEASING ANY INFORMATION ABOUT VICTIM. THE BODY WAS DISCOVERED AS FIREFIGHTERS COMBED THROUGH WHAT WAS LEFT OF THE HOME. SOME NEIGHBORS WHO WERE NEARBY AT THE TIME SAY THEY RUSHED TO HELP, BUT THERE WAS NOTHING THEY COULD DO. BY THE TIME WE GOT HERE, THE WHOLE HOUSE WAS IN FLAMES. IT WAS TORCHED. OTHER NEIGHBORS REPORTED HEARING AN EXPLOSION BEFORE SEEING THE FIRE. IT WAS A BIG BOOM. THE HOUSE SHOOK A LITTLE. THEN I LOOKED OUT THE WINDOW. THE SMOKE WAS GOING ANYWHERE. IT WAS ENGULFED. THE ROOF GAVE AND THE FIRES WERE JUST SPOUTING THROUGH THE ROOF. THE DEPUTY FIRE CHIEF DESCRIBED THE FIRE AS INTENSE AND SAID THEY HAD TO FIGHT HARD TO CONTAIN IT. THEY WERE ABLE TO LIMIT THE DAMAGE TO JUST THE HOUSE. YOU MAY BE ABLE TO SEE SOME FIREFIGHTERS UP THERE WORKING ON THE SECOND FLOOR. NOW AT THIS POINT, ONCE AGAIN, NO INFORMATION ABOUT THE VICTIM IS BEING RELEASED PENDING THOSE AUTOPSY RESULTS. ALSO NOTIFICATION OF THE NEXT OF KIN.